Asymptotic analysis of fair scheduling in the OFDM systems

Orthogonal frequency division multiplexing (OFDM) is one of the promising techniques in the next generation high-speed data rate wireless networks for its ability to combat the intersymbol interference(ISI), and fair scheduling algorithms are used to utilize the independence of the fading statistics of different user to improve the spectral efficiency. In this paper, we try to analysed the performance of fair scheduling algorithms in the OFDM systems and choose the appropriate subband size to tradeoff between the throughput and the channel feedback. We show that asymptotic scheduling gain of fair scheduling algorithms in the OFDM system increases as the number of user increases and decreases with the average received SNR. We also present the distribution of the averaged received signal-to-noise-ratio (SNR) in a subband, give a formula to evaluate the scheduling gain approximately, and point out that the maximal eigenvalue is a good indicator to choose the appropriate subband size. It is shown that the appropriate subband number is 16 for channel A or 32 for channel B.